no sound after upgrade

hello, I own a 98 navigator and wanted to install an aftermarket radio to it. I know that it has a 'premium sound' system so i purchased this and this ok so my problem is this, after I wire everything and plug in the radio, the radio turns on but there is no sound. I play around with the Interface Adapter, setting different gains and such and still no sound. I grabbed a set of speaker cable and put a battery to the ends so i could here the hiss and nothing. what could be my problem, thanks jdawg

My recommendation would be to ditch the interface adapter and just bypass the amp altogether.  It sounds like somehow the amp is the source of your problem, or possibly the interface adapter you are using to integrate it.